Traditionally, card readers are associated with an access point to a system or building. In a physical access control system, card readers are commonly located at a door and each person who is authorized to enter the premises carries an access card that interacts with the readers. The access card can contain a radio-frequency identification (RFID) chip or an application-specific integrated circuit (ASIC) chip which stores a code number in its memory. The code number can be a single value or stored in multiple fields that correspond to, e.g., a serial number and a facility code to designate a building or series of buildings. The ASIC or RFID chip within the card is connected to an antenna, and the card is able to communicate to the reader using an inductive coupling, commonly referred to as RFID.
The reader typically sends out an interrogating signal at 125 KHz to 134 KHz, known as Low Frequency (LF). Other frequencies are also used; for example, another frequency band known as HF operates at the singular frequency of 13.56 Mhz. The card is presented to the reader (e.g., by being placed in proximity to the reader), and the reader reads a message from the card. The reader is programmed to strip the message of its overhead structure, and reformat the message in a standardized data stream which the reader sends to a control panel. For example, the standardized format can be the so-called Wiegand code. The control panel may or may not recognize the card as belonging to the population of authorized entrants. If the card is recognized as authorized, the panel takes appropriate action to open the door which generally involves setting a relay that sends an electric current to activate a device at the door (e.g., a magnetic strike or lock).
FIG. 1 is a block diagram of a system 100 comprising a card access control reader 103 connected to a control panel 101, as illustrated in the art. The reader 103 is connected to the control panel 101 via connection 102 (e.g., Wiegand interface). A card 104 is presented to the reader 103 (e.g., by passing the card in close proximity to the reader, or touching the card to the reader) using an RFID signal 105, and the reader 103 receives a message from the card 104.
Traditionally, card readers are programmed to be responsive to one type of card. Furthermore, the reader generally accepts a card only if the reader has been programmed to understand or acknowledge certain predetermined data formats coming from the card. Types of data formats include, but are not limited to, Frequency Shift Keying (FSK), Amplitude Modulation (AM) and Phase Shift Keying (PSK). The length of the messages can be different, ranging typically from 24 bits to 64 bits. The means by which the card indicates the beginning and end of a message also includes many different types, for example, Manchester encoding cessation or embedding of a string of ones or zeroes to mark the data field boundaries. Also, within the data fields once they are decoded, it is typical to have facility code and serial numbers in field lengths that are different for different situations.
The reader does not usually make the final decision as to whether a card is valid or not. If the card is of the correct format, the reader sends the now-decoded data stream via a message to a control panel which may be connected to a number of readers. The data stream is typically of the aforementioned Wiegand type, which is a self-clocking three wire protocol used in many access control systems, or utilizes serial communication with RS-232 or RS-485 based protocols. The control panel includes or is coupled to a database that consists of a list of authorized card numbers as well as facility codes. When the panel sees a card that is authorized, the panel operates a relay connected to one or more electromechanical devices on the door, such as a magnetic strike, and the door is allowed to open.
Although the card reader at the door is not typically responsible to make the final decision about the validity of a card, it is advantageous in certain circumstances for the reader to contain a list of disenrolled or invalid cards (also called a revocation list) or to check proper data integrity and formatting, so that the reader itself decides not to send to the control panel a code that was previously taken off the allowed list or is not properly read.
The reader is typically equipped with a light-emitting diode (LED) and a sounding device (e.g., a beeper). The LED and beeper devices can be programmed to behave in different ways depending on the reader's ultimate action.
During its life, a card reader may require maintenance such as:                Changing the data format of cards that should be acceptable to the reader;        Configuring the LED to light up or blink when a card is read, is accepted, or configuring the LED not to light up at all;        Configuring the beeper to beep when a card is read, is accepted, or configuring the beeper not to beep at all;        Running diagnostic routines such as: verifying that the power supplies are within limits, the tamper switch has not been disturbed, or other similar routines; and        Loading a list of cards previously accepted but now invalid or disenrolled from the access control system.        
Typically, card reader maintenance requires a technician to visit the location of the reader and perform certain manual tasks to the reader. Such maintenance increases the costs associated with the system and adds time to complete the maintenance process.